KR20160113893A - Single focus lens and photographing lens having the same - Google Patents

Abstract

Disclosed are a single focus lens, and an imaging device having the same. The disclosed imaging device comprises, in order from the object side to an upper side: a first lens group having a negative refractive power; a second lens group having a positive refractive power and preventing hand from shaking; a third lens group having the negative refractive power and performing focusing; and a following group disposed on an upper side of the third lens group.

Description

[0001] The present invention relates to a single focus lens and a photographing device including the single focus lens.

An exemplary embodiment relates to a small-sized short-focus lens including a group of camera shake correction lenses and a group of focusing lenses, and a photographing apparatus including the same.

A photographing apparatus using a solid-state imaging element such as a CCD (Charge-Coupled Devices) type image sensor or a CMOS (complementary metal-oxide semiconductor) type image sensor is widely used. BACKGROUND ART In a photographing apparatus using a solid-state image pickup device such as a digital camera, an interchangeable lens system, and a video camera, users have a demand for high resolution and high quality. 2. Description of the Related Art [0002] A photographing apparatus using a solid-state image sensing device is suitable for miniaturization, and has recently been applied to a small information terminal including a cellular phone.

However, it is not easy to satisfy high resolution and high quality while miniaturizing a photographing apparatus or a lens system.

An exemplary embodiment provides a small-sized short-focus lens including a group of hand-shake correction lenses and a group of focusing lenses.

An exemplary embodiment provides a photographing apparatus including a hand shake correction lens group and a focusing lens group and including a small-sized short-focus lens.

The short focal lens according to the exemplary embodiment,

Which are arranged in order from the object side to the image side,

A first lens group having negative refractive power;

A second lens group having positive refractive power and moving in a direction orthogonal to the optical axis to perform shaking prevention;

A third lens group having a negative refractive power and correcting a focus position difference according to an object position change; And

And a subsequent lens group disposed on the upper side of the third lens group.

The single focal lens can satisfy the following formula.

<Expression>

1.0? La / f? 1.5

Here, La represents the distance from the object-side surface of the most object-side lens in the first lens unit to the image surface, and f represents the total focal length.

The single focal lens can satisfy the following formula.

<Expression>

-0.5? F3 / f? -0.1

Here, f3 represents the focal length of the third lens unit, and f represents the total focal length.

The first lens group may be composed of one meniscus whose upper surface is convex.

A diaphragm may be provided between the second lens group and the third lens group.

And the second lens group may include at least one aspherical surface.

And the third lens group may be composed of one aspheric lens.

The aspherical lens of the third lens group may have a refractive index of 1.7 or less.

And the aspherical lens of the third lens group may have an Abbe number of 55 or more.

And the subsequent group may include a cemented lens and a negative lens.

The cemented lens may include a positive lens and a negative lens.

The Abbe number difference between the positive lens and the negative lens of the cemented lens may have a range of 7 or more.

The negative lens may be an aspherical lens.

The lens on the uppermost side of the succeeding lens group may be a meniscus lens convex upward.

A photographing apparatus according to an exemplary embodiment includes a short focus lens and an image sensor that receives an image formed by the short focus lens, wherein the short focus lens is a photographing apparatus.

Which are arranged in order from the object side to the image side,

A first lens group having negative refractive power;

A second lens group having positive refractive power and moving in a direction orthogonal to the optical axis to perform shaking prevention;

A third lens group having a negative refractive power and correcting a focus position difference according to an object position change; And

And a subsequent lens group disposed on the upper side of the third lens group.

The single-focus lens according to the exemplary embodiment includes a group of camera shake correction lenses and a group of focusing lenses, and is manufactured in a small size, so that high quality pictures and movies can be photographed.

Fig. 1 shows a short focus lens according to an exemplary first numerical example at an infinite distance and a near distance, respectively.
Fig. 2 shows aberration diagrams of the short focal lens shown in Fig.
Figure 3 shows a short focal lens according to an exemplary first numerical example at an infinite distance and a near distance, respectively.
Fig. 4 shows aberration diagrams of the short focal lens shown in Fig.
Fig. 5 shows a short focal lens according to an exemplary third numerical example at an infinite distance and a near distance, respectively.
6 shows aberration diagrams of the short focal lens shown in Fig.
7 shows a photographing apparatus according to an exemplary embodiment.

Hereinafter, a short-focus lens and a photographing apparatus including the same according to an exemplary embodiment will be described in detail with reference to the accompanying drawings.

FIG. 1 illustrates a monofocal lens 100 according to one embodiment.

The short focal lens 100 is arranged in order from the object side O to the image side I and includes a first lens group L1 having a negative refractive power, a second lens group L2 having a positive refractive power, A third lens group L3 having refractive power, and a rear lens group disposed on the image side I of the third lens group L3.

The second lens group L2 may move in a direction perpendicular to the optical axis to prevent camera shake. The third lens group L3 may be a focusing lens group for correcting a focus position difference according to an object position change.

Hereinafter, an image side indicates a direction in which an image plane is formed, and an object side indicates a direction in which a subject exists. Hereinafter, the object side surface of the lens indicates the lens surface on the side where the subject is located, and the upper side surface can indicate the lens surface on the side having the upper surface.

The first lens group L1 may be composed of, for example, one lens having a negative refractive power. The lens of the first lens group L1 may be a meniscus lens having a concave surface on the object side.

The second lens group L2 may be composed of, for example, one lens. The one lens may include at least one aspherical surface. The second lens group L2 may include, for example, a biconvex lens. The second lens unit L2 can effectively correct the up-shift due to the vibration of the entire lens due to the external vibration such as hand shake of the photographer. Further, the second lens unit L2 can be formed with both convex aspheric surfaces to easily correct the spherical aberration of the entire lens system, and the performance deterioration due to the aberration change can be reduced at the time of the overtight correction.

The third lens group L3 may include, for example, a concave meniscus lens at the image side (I). The meniscus lens may be, for example, an aspherical lens. The third lens unit L3 may operate as a focusing lens for correcting the focus position difference according to the change of the object distance. The lens of the third lens group L3 may have a refractive index of 1.7 or less, for example. The lens of the third lens group L3 may have a refractive index in the range of 1.4 to 1.7, for example. The lens of the third lens group L3 may have an Abbe number of 55 or more, for example. The lens of the third lens group L3 may have an Abbe number in the range of 55 to 80, for example. By using such a material, the weight of the lens can be reduced by a specific gravity lower than that of the high-refractive index material, and high-speed auto focusing can be performed. In addition, the third lens unit L3 includes an aspherical lens, and it is possible to reduce the variation of the curvature of field curvature according to the change of the object distance.

A diaphragm ST may be provided between the second lens group L2 and the third lens group L3. Since the first lens group L1 on the object side O of the stop ST includes the concave meniscus lens, it is possible to effectively correct the sagittal coma aberration occurring in the large-diameter lens system, It is possible to realize a single-focus lens having a large diameter and a small size.

The distance between the first lens group L1 and the second lens group L2 and the distance between the second lens group L2 and the diaphragm are respectively set to be between the third lens group L3 and the subsequent lens group L4 The spherical aberration and the astigmatism can be corrected effectively.

The subsequent group L4 may include, for example, cemented lenses 41 and 42 and a single lens 43. [ The cemented lens may include a positive lens 41 and a negative lens 42, for example. The lens 43 may have a negative refractive power. The lens 43 may be a meniscus lens convex upward. The lens 43 disposed on the uppermost side I of the subsequent group L4 may include, for example, at least one aspherical surface. The lens 43 may be a double-sided aspheric lens. The positive lens 41 and the negative lens 42 of the cemented lens may have an Abbe number of 7 or more. Thereby, the axial chromatic aberration can be corrected effectively. In addition, the meniscus aspheric lens on the uppermost side of the succeeding lens group L4 can easily correct the astigmatism and the surface curvature aberration of the entire short focal lens.

The image of the subject can be incident on the image plane IMG through the first lens group L1, the second lens group L2, the third lens group L3 and the succeeding group L4. The upper surface IMG may be, for example, an image pickup element surface or an image sensor surface. The image sensor may comprise, for example, CMOS or CCD.

At least one optical filter (OF) may be provided between the succeeding lens group (L4) and the image plane (IMG). The optical filter OF may include at least one of, for example, a low pass filter, an IR-cut filter, and a cover glass. For example, when an infrared cut filter is provided as an optical filter, visible light is transmitted, and infrared light is emitted to the outside, so that infrared light is not transmitted to the upper surface. However, it is also possible to construct a photographing lens without an optical filter.

The short focal length lens according to the exemplary embodiment performs image stabilization by the second lens unit and performs focusing by the third lens unit, thereby enabling high-quality photographing and moving image shooting, and reducing the number of lenses to realize miniaturization .

The diaphragm (ST) is arranged on the upper side (I) of the camera-shake correcting lens group, and the driving part for driving the camera-shake correcting lens group and the supporting part for supporting the diaphragm Can be produced. Thus, even if the camera-shake correction function is added, it is possible to minimize the size of the imaging device due to the driver of the camera-shake correction group.

Further, it is possible to miniaturize the actuator for driving the focusing lens group by constituting the focusing lens group (the third lens group) as one lens, and the auto focusing can be performed at high speed.

The single focus lens 100 according to the exemplary embodiment can satisfy the following expression.

1.0? La / f? 1.5 (1)

Here, La represents the distance from the object-side surface of the most object-side lens in the first lens unit to the image surface (total length), and f represents the total focal length.

(La / f) exceeds the upper limit value of Equation (1), the total length of the short focal length lens compared to the focal length becomes very large, which is advantageous in securing the performance, but it may be difficult to form a small lens barrel. (La / f) exceeds the lower limit value of Equation (1), it is advantageous for a small-sized lens barrel configuration, but it is difficult to correct the aberration and it may become difficult to secure the optical performance.

The single focus lens 100 according to the exemplary embodiment can satisfy the following expression.

-0.5? F3 / f? -0.1 (2)

Here, f3 represents the focal length of the third lens unit, and f represents the total focal length.

If (f3 / f) is smaller than the lower limit value in Equation 2, the movement amount for autofocusing of the third lens unit can be reduced, which is advantageous for miniaturization, but the manufacturing sensitivity of the third lens unit increases and aberration correction becomes difficult have. (f3 / f) is larger than the upper limit value, the amount of movement for auto focusing may increase, which may make miniaturization of the entire lens system difficult.

The monofocal lens according to the exemplary embodiment may have an angle of view ranging, for example, from 40 to 70 degrees. The F-number may have a range of 1.4-3.5. A single focus lens according to an exemplary embodiment may include, for example, an image sensor corresponding to a 35 mm film size.

On the other hand, the definition of the aspheric surface used in the short focal lens according to the exemplary embodiment is as follows.

The aspheric surface shape can be expressed by the following equation with the optical axis direction as x axis and the direction perpendicular to the optical axis direction as the y axis, assuming that the traveling direction of the ray is positive. Where x is the distance from the vertex of the lens to the optical axis direction, y is the distance in the direction perpendicular to the optical axis, K is the conic constant, A, B, C, D, ... C is an inverse number (1 / R) of the radius of curvature at the apex of the lens, respectively.

<식 3>

<Formula 3>

In the present invention, a monofocal lens can be realized through numerical embodiments according to various designs as follows.

In the table of each numerical embodiment, the lens surface numbers (1, 2, 3,... N) are sequentially arranged in order from the object side O to the image side I, . F is the total focal length of the short focal lens, Fno is the F number, 2w is the angle of view, OBJ is the object (subject), RDY is the radius of curvature, THI is the thickness of the lens, Nd represents the refractive index, and Vd represents the Abbe number. ST represents aperture and ASP aspheric surface.

&Lt; First Numerical Embodiment >

Fig. 1 shows a monofocal lens according to the first numerical example, and the following shows design data of the first numerical embodiment. Fig.

f; 44.9 Fno; 2.46 2w; 52.76

Lens face RDY THI Nd Vd OBJ: INFINITY INFINITY One -28.82927 1.300000 1.752110 25.047 2 -80.13103 0.800000 3 25.22000 4.263293 1.739600 49.110 ASP:
K: -0.061558
A: -. 129335E-04 B: 0.108302E-07 C: - 532162E-09 D: 0.291536E-11 4 -38.83606 1.000000 ASP:
K: 0.052227
A: 0.177798E-04 B: - 664286E-07 C: 0.220700E-10 D: 0.142804E-11 ST INFINITY D1 6 873.72519 1.300000 1.514700 63.779 7 18.08647 D2 ASP:
K: 0.737055
A: -. 233004E-04 B: 0.182605E-06 C: - 205479E-08 D: 0.164279E-10 8 49.77955 4.716424 1.8810035 40.138 9 -13.24554 1.300000 1.6989493 30.065 10 83.32283 9.511499 11 -31.81216 2.223034 1.514700 63.779 ASP:
K: 0.087308
A: - 177753E-03 B: 0.287632E-06 C: - 201214E-08 D: - 673457E-11 12 -78.70767 17.000000 ASP:
K: 11.506874
A: - 136722E-03 B: 0.455649E-06 C: - 210447E-08 D: 0.375407E-11 13 INFINITY 3.000000 1.5167983 64.197 14 INFINITY 0.967390 IMG INFINITY

The following shows the variable distance of the first numerical embodiment.

Variable distance Infinity Macro D1 1.8613 4.364 D2 7.7245 5.2217

The nearest distance may be, for example, 400 mm.

FIG. 2 shows longitudinal spherical aberration, astigmatic field curves, and distortion at an infinite distance and a nearest distance of a short focal lens according to the first numerical example. Tangential field curvature (T) and sagittal field curvature (S) are shown for the curvature of field.

&Lt; Second Numerical Embodiment >

Fig. 3 shows a monofocal lens according to the second numerical example, and the following shows design data of the second numerical embodiment.

f; 46.3 Fno; 2.46 2w; 51.4

Lens face RDY THI Nd Vd OBJ: INFINITY INFINITY One: -37.71847 2.500000 1.741274 27.7522 2: -190.46052 3.254609 3: 23.52585 4.696218 1.739913 48.9114 ASP:
K: 0.021743
A: - 116656E-04 B: 0.147817E-07 C: - 580821E-09 D: 0.199731E-11 4: -57.69000 1.000000 ASP:
K: 1.530694
A: 0.157708E-04 B: - 691809E-07 C: 0.165013E-11 D: 0.816926E-12 ST: INFINITY D1 6: 100.27104 1.400000 1.555334 49.0224 7: 17.21972 D2 ASP:
K: 0.630755
A: - 269634E-04 B: 0.116552E-06 C: - 142481E-08 D: 0.247552E-11 8: 37.16506 8.326005 1.881003 40.1388 9: -14.72995 1.400000 1.698949 30.0657 10: 39.31221 6.938978 11: -96.54037 2.200000 1.521888 60.3741 ASP:
K: -5.314901
A: - 181046E-03 B: 0.150219E-06 C: - 294349E-08 D: - 613699E-11 12: -1000.00000 21.000000 ASP:
K: -20.000000
A: - 147462E-03 B: 0.339083E-06 C: - 293061E-08 D: 0.786007E-11 13: INFINITY 3.000000 1.516798 64.1983 14: INFINITY 0.975592 IMG: INFINITY

The following shows the variable distance of the second numerical embodiment.

Variable distance Infinity Nearest street D1 1.5 4.2254 D2 6.7842 4.0587

Fig. 4 shows the longitudinal spherical aberration, astigmatic field curves, and distortion of an infinite distance and a near distance of a short focal lens according to the second numerical example.

&Lt; Third Numerical Embodiment >

Fig. 5 shows a monofocal lens according to the third numerical example, and the following shows design data of the third numerical example. Fig.

f; 44.0 Fno; 2.86 2w; 53.3

Lens face RDY THI Nd Vd OBJ: INFINITY INFINITY One: -23.71513 1.100000 1.741540 27.5550 2: -51.34736 0.800000 3: 18.02034 3.917639 1.764534 50.1012 ASP:
K: -0.304371
A: - 199965E-04 B: - 452645E-07 C: - 674608E-09 D: - 478172E-11 4: -42.20775 1.000000 ASP:
K: 2.034216
A: 0.182519E-04 B: - 457578E-07 C: - 399010E-09 D: - 260391E-11 ST: INFINITY D1 6: 43.30592 1.100000 1.682643 31.7616 7: 13.73679 D2 ASP:
K: 0.650602
A: -. 120154E-04 B: - 247212E-06 C: 0.190292E-08 D: - 969801E-10 8: -91.92472 3.795495 1.732872 52.2029 9: -11.54214 1.100000 1.546080 45.3692 10: -62.71292 6.108159 11: -43.74800 2.200000 1.575843 68.8668 ASP:
K: -13.463725
A: -. 198852E-03 B: 0.345893E-06 C: - 668328E-08 D: 0.195671E-10 12: -1000.00000 18.000000 ASP:
K: 20.000000
A: -. 151948E-03 B: 0.362706E-06 C: - 313880E-08 D: 0.711286E-11 13: INFINITY 3.000000 1.516798 64.1983 14: INFINITY 0.949614 IMG: INFINITY

The following shows the variable distance of the third numerical example.

Variable distance Infinite distance Nearest street D1 1.5 2.9493 D2 5.3787 3.9294

FIG. 6 shows longitudinal spherical aberration, astigmatic field curves, and distortion at an infinite distance and a near distance of a short focal lens according to the third numerical example.

The following shows that the monofocal lenses according to the first to third numerical examples satisfy the equations (1) and (2).

First numerical example Second Numerical Embodiment Third Numerical Embodiment Equation 1 1.268 1.4 1.136 Equation 2 -0.8 -0.81 -0.68

The single-focus lens according to the exemplary embodiment can be applied to a small-sized photographing apparatus, and can perform high-quality photographing and movie shooting by performing anti-shake and focusing. In addition, the camera shake correcting unit and the focusing lens unit can be made compact and lightweight, and a photographing apparatus can be made compact. In addition, the focusing lens group is made up of a small and lightweight lens, which enables quick auto focusing. The short focal lens according to the exemplary embodiment can be applied to a photographing apparatus employing an image sensor. The photographing apparatus according to the exemplary embodiment is applicable to various photographing apparatuses such as a digital camera, an interchangeable lens camera, a video camera, a mobile phone camera, a mirrorless camera, and a camera for a small mobile device.

FIG. 7 shows an example of a photographing apparatus 110 having a short focal lens according to an exemplary embodiment. The photographing apparatus 110 may include a photographing lens 100 and an image sensor 112 that receives an optical image formed by the photographing lens 100 and converts the optical image into an electrical image signal. As the photographing lens 100, short-focus lenses described with reference to Figs. 1 to 6 may be employed. The photographing apparatus may include a recording means 113 recording information corresponding to the photoelectrically-converted object from the image sensor 112, and a finder 114 for observing a subject image. In addition, a display unit 115 for displaying a subject image may be provided. Here, an example in which the viewfinder 114 and the display unit 115 are separately provided is shown, but only the display unit can be provided without a viewfinder. The photographing apparatus shown in Fig. 7 is merely an example, and the present invention is not limited thereto.

The above-described embodiments are merely illustrative, and various modifications and equivalent other embodiments are possible without departing from the scope of the present invention. Therefore, the scope of the true technical protection according to the embodiment of the present invention should be determined by the technical idea of the invention described in the following claims.

L1: first lens group, L2: second lens group
L3: the third lens group, L4: the succeeding lens group

Claims (15)

Which are arranged in order from the object side to the image side,
A first lens group having negative refractive power;
A second lens group having positive refractive power and moving in a direction orthogonal to the optical axis to perform shaking prevention;
A third lens group having a negative refractive power and correcting a focus position difference according to an object position change; And
And a subsequent lens group disposed on the upper side of the third lens group. The method according to claim 1,
A short focal length lens satisfying the following expression.
<Expression>
1.0? La / f? 1.5
Here, La represents the distance from the object-side surface of the most object-side lens in the first lens unit to the image surface, and f represents the total focal length. The method according to claim 1,
A short focal length lens satisfying the following expression.
<Expression>
-0.5? F3 / f? -0.1
Here, f3 represents the focal length of the third lens unit, and f represents the total focal length. The method according to claim 1,
And the first lens group is composed of one meniscus whose upper surface is convex. The method according to claim 1,
And a stop is provided between the second lens group and the third lens group. The method according to claim 1,
And the second lens group includes at least one aspherical surface. The method according to claim 1,
And the third lens group is composed of one aspheric lens. 8. The method of claim 7,
And the aspheric lens of the third lens group has a refractive index of 1.7 or less. 8. The method of claim 7,
And the aspherical lens of the third lens group has an Abbe number of 55 or more. 8. The method according to any one of claims 1 to 7,
Wherein the subsequent group includes a cemented lens and a negative lens. 11. The method of claim 10,
Wherein the cemented lens includes a positive lens and a negative lens. 12. The method of claim 11,
Wherein the Abbe number difference between the positive lens and the negative lens of the cemented lens has a range of 7 or more. 12. The method of claim 11,
Wherein the negative lens is an aspherical lens. 10. The method according to any one of claims 1 to 9,
And the uppermost lens of the succeeding lens group is a meniscus lens convex upward. 10. A monofocal lens according to any one of claims 1 to 9, And
And an image sensor for receiving the image formed by the short focus lens.

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